1. Field of the Invention
The invention relates to a method for producing metal panels.
2. Description of the Related Art
Such a method is generally known. An example of such a method is the foil drawing method known as Ribbon Growth on Substrate (RGS). Here a casting frame is filled with liquid silicon, for example, and a substrate band is used which is driven so that a surface of a substrate band comes into contact with the metal melt, where the casting frame remains in a certain position and the substrate band passes underneath the casting frame. On the side of the casting frame from which the substrate band leaves the casting frame, a crystallised metal foil escapes at this point. This foil is divided into pieces, which pieces can serve as a basis for producing solar cells, for example.
It is known that structures may be installed in the surface of a solar cell in order to reduce the reflection of the incident light on the surface. One example of this is 15 achieved by providing grooves so that the surface of the solar cell is increased, thereby increasing the efficiency of the solar cell.
Patent publication U.S. Pat. No. 5,704,992 describes a method in which V-shaped grooves in a foil are ground by means of a special saw blade. The saw blade has a pointed profile and rotates at high speed. According to the publication U.S. Pat. No. 4,608,451, a structure is also installed in the surface of a metal foil. In the latter publication grooves are etched into the foil. A certain mask is fitted on the foil, whereupon it is brought into contact with an etching material. In this case V-shaped grooves may also be formed in the foil. It is also possible, by etching, to fit irregular or 2-dimensional structures in order to achieve the same effect.
However, it is necessary, using these techniques, to process the metal foil further after manufacture in order to obtain the desired structure on the surface.
Publication JP 2001206798 describes a device with which metal panels can be produced which are formed by means of a foil drawing method. A rotary substrate is used on which crystallisation of silicon takes place. The surface of the substrate may be unmachined, whereby the metal panels produced on a surface are given a saw tooth structure, for example. This enlarges the effective area, resulting in improved efficiency in solar cells.
The foil drawing method is ideal for producing very thin foils. Foils can be produced with a thickness of less than 250 μm. The major advantage of this method is that the quantity of silicon per panel, for example a solar cell, is very limited. A disadvantage of the very thin metal panels is that they can easily break. This risk is real, particularly in the further production of solar cells.